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J/A+A/324/505      Core velocity dispersions of globular clusters (Dubath+ 1997)

Core velocity dispersions for 25 Galactic and 10 old Magellanic globular clusters Dubath P., Meylan G., Mayor M. <Astron. Astrophys. 324, 505 (1997)> =1997A&A...324..505D (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, globular ; Radial velocities ; Velocity dispersion Keywords: (Galaxy:) globular clusters: general - stars: kinematics - techniques: radial velocities - galaxies: star clusters - Magellanic Clouds Abstract: We present, for 25 Galactic and 10 old Magellanic globular clusters, projected velocity dispersion (σp) measurements obtained by applying a cross-correlation technique to integrated-light spectra. In order to understand and estimate the statistical errors of these measurements due to small numbers of bright stars dominating the integrated light, we provide an extensive discussion based on detailed numerical simulations. These errors are smaller if the integration area is larger and/or the cluster concentration higher. The simulations show that measurements are reliable when the integrated light within the integration area is brighter than a given magnitude. The statistical errors on the σp measurements of Magellanic globular clusters are small because of a physically large integration area, whereas they can be important for measurements carried out over small central areas in Galactic clusters. The present observational results are used to outline a few characteristics of the globular cluster fundamental plane. In this respect, the old Magellanic globular clusters appear similar to the Galactic clusters. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table67 98 44 Radial velocities and core velocity dispersions
Byte-by-byte Description of file: table67
Bytes Format Units Label Explanations
1- 3 A3 --- Loc Localication (Gal, LMC or SMC) 5- 8 A4 --- Obs Observation number 10- 14 A5 --- NGC NGC number 16- 21 F6.1 km/s HRV Derived heliocentric radial velocity 23- 25 F3.1 km/s e_HRV rms uncertainty on HRV 27- 30 F4.1 km/s sigCCF Standard deviation of the cross-correlation function (CCF) 32- 34 F3.1 km/s e_sigCCF rms uncertainty on sigCCF 36- 40 F5.3 % Depth Relative depth of the CCF 42- 45 F4.1 --- S/N Signal-to-noise ratio of the spectrum 47- 50 F4.2 km/s eps Uncertainty epsilon of HRV and sigCCF due to the spectrum noise 52- 54 F3.1 km/s sigref Value used for the intrinsic standard deviation from the standard CCFs 56- 59 F4.2 km/s e_sigref rms uncertainty on sigref 61- 64 F4.1 km/s sigpObs ? Observed cluster core projected velocity dispersion 66- 68 F3.1 km/s E_sigpObs ? Error in sigpObs (upper limit) due to the instrumental error and to the spectrum noise 70- 72 F3.1 km/s e_sigpObs ? Error in sigpObs (lower limit) due to the instrumental error and to the spectrum noise 74- 76 F3.1 km/s StatErru ? Statistical error (upper limit) due to the small sample of bright stars observed through the slit 77 A1 --- u_StatErru Uncertainty flag on StatErru 79- 81 F3.1 km/s StatErrl ? Statistical error (lower limit) due to the small sample of bright stars observed through the slit 83- 86 F4.1 km/s sigp ? Calculated cluster core projected velocity dispersion (1) 88- 90 F3.1 km/s E_sigp ? Error in sigp (upper limit) (2) 91 A1 --- uEsigp Uncertainty flag on E_sigp 93- 95 F3.1 km/s e_sigp ? Error in sigp (lower limit) (2)
Note (1): sigp includes the contribution from the statistical error simulations Note (2): Uncertainty, including the contribution from the statistical error
Acknowledgements: Pierre Dubath
(End) Patricia Bauer [CDS] 20-Jan-1997
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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